Modern automatic welding machines utilize welding wire which should be fed continuously at high velocities, uniformly, without undesirable twists and with a minimum of interruptions. It is therefore desirable to package the welding wire in coils of the longest length practically possible for its efficient and economical handling and to minimize the number of times the empty containers are replaced by new ones for feeding the welding machines.
The wire is packaged by special winding machines which continuously coil the wire in the annular space within the container formed typically between a central core member and the container wall. Usually, the container is provided with a variety of devices for retaining the wire in its coiled form and to avoid its tangling during transportation and particularly during unwinding.
It is also desirable to minimize the overall costs involved in the packaging and handling of the welding wire from the wire manufacturing plant to the plant of ultimate usage. The containers currently used for packaging welding wire are cylindrical drums made from any of a variety of materials, for example, reinforced composites or other thick and strong materials with several metallic rings at their upper and lower lids. These are designed to withstand rough handling during transport. These drum-type containers are expensive due to the high cost of materials and their special fabrication. After the welding wire is consumed by the welding machines, usually in plants remote from the place where the welding wire is manufactured, then the empty containers must be temporarily stored, occupying excessive space until they can be properly disposed of. Sometimes, the empty drums may be transported back to the welding wire manufacturing plant at a high cost because of the volume they occupy. Alternatively, it is not easy to dispose of these containers, because they can not easily be destroyed and because the materials they are made of are not readily recyclable.
An example of the containers currently in use is shown in U.S. Pat. No. 5,105,943 to Lesko et al. This patent describes a cylindrical container (a drum) made of thick paperboard which includes a tubular core co-axially extending in the drum thus leaving an annular space where the welding wire is wound in the form of a multitude of layers of looped wire. A looped strap is fixed at the bottom of the tubular core and one end of an elastic cord is fixed to said strap and its other end to a diametrically extending bar which presses downwardly a top disc, which can be formed by two semicircular sections, thus maintaining the wire mass in place while being transported.
The Lesko container, although offering the advantage of utilizing a low-cost material, does not offer a good mechanical resistance to forces applied to its circular wall 12, therefore requiring an excessive amount of cardboard material for its fabrication. Also, it presents a drawback in that the retainer disk 42 can not be adjusted to variable heights of the wire mass, because the core 28 limits its action. Therefore, the container must always be filled with welding wire to a height higher than said core 28. The retainer disk 42 must be removed for unwinding the wire.
An improvement to the device for preventing the welding wire from tangling is described in U.S. Pat. No. 5,746,380 to Chung. Chung discloses a combination of a number of elements including bead packages 4′ which are distributed over the top layers of wire and two rings 5 and 6 which are pressed by elastic bands 7 and 7′ against the wire coil 8. Prior to drawing the wire out of the container, the pressing short pipes 3 and buffer rings 5 and 6 are removed and some bead packages 4′ are torn, and the beads 4 are scattered over the coiled welding wire to prevent tangling. The wire 9 then goes smoothly through the beads 4 without tangling. When the wire is to be fed to automatic welding machines, all these elements must be removed and recovered for further use in other containers. Chung also shows a guiding cover 1′ of conical form which is fitted over the top of the container having a wire guiding tube 11 through which the wire 9 is passed for its orderly unwinding. Scattering of the beads 4 over the wire 9 is impractical, since they have to be repackaged for further use, causing unnecessary material costs, increased labor time, and added weight with resulting increased shipping cost for the heavier wire package.
U.S. Pat. No. 4,869,367 to Kawasaki et al. proposes to eliminate the internal tubular core 2 of the prior art; to use a container of steel and also a different design for a retaining and guiding member 4 which descends by gravity as the wire is withdrawn from the container. The retaining member 4 has a ring form having a circular hole 17 at its center to permit withdrawal of wire 3 therethrough. The retaining member 4 has several resilient members 5 (FIG. 4 embodiment) for contact with the inner wall 1 of the container to prevent the wire from passing through the space close to the inner wall of the container. The resilient members 120 (FIG. 6 embodiment) must be flexible enough to not cause excessive drag force while moving in contact with the wall 1 and at the same time be rigid enough to present an effective resistance against the wire if it tends to pass through the area of contact of said resilient members. The retaining member of Kawasaki adds to the cost of the packaging and transport because of the special type of materials used; and it may not provide the desired effect, because it may easily assume a non-horizontal position due to non-uniform friction between said resilient members 120 and the wall of the container.
An improvement to the cylindrical container shown in the above patent is described in U.S. Pat. No. 5,819,934 to Cooper. Cooper shows a drum-type container A having a central tubular core 30 and a simplified way of forming a loop 80, 200, 220, 250 or 266 at the bottom of the core 30 in order to secure by means of a hook 76 one end of an elastic band 72 that pulls down on a bar 70 and thereby on an annular disk member 52, which in turn presses on and retains the wire W in the space 40 during shipping and storage of the container. The container of Cooper however presents the same drawbacks as Lesko, described above.
In the interest of providing an effective device for the smooth withdrawal of welding wire, another proposal for such a device illustrated as used in cylindrical containers is described in U.S. Pat. No. 5,277,314 to Cooper et al. This patent discloses a retainer ring 110 for a cylindrical container of welding wire comprising a generally flat outer portion with an outer periphery fitting into the wall of the container, and a bell-mouth portion though which the wire is payed out. The retaining ring of Cooper is expensive because of its special design.
A further example of a cylindrical container for welding wire is described in U.S. Pat. No. 5,758,834 to Dragoo et al. Dragoo shows a cylindrical wire container 10 including a wire control apparatus 100 mounted at the top of an inner tubular core 25 which comprises a ring 105 and is provided with a plurality of fingers 140 mounted on said ring. This structure differs from the typical prior art in that the welding wire is payed out past the outer periphery of the ring 105, rather than through the ring's center hole. A plurality of tie-down wires 120 serve as upwardly sloping diverter members and also prevent the welding wire from entering into the space between the ring and the core. The fingers extend into contact with the wall of the container to insure that the welding wire is forced against the inner surface of the container as the welding wire is withdrawn therepast. The stiffness of the fingers is such that the wire cannot by itself uncoil past the fingers and exit the drum, however at the same time the fingers must not be so stiff as to impede purposeful withdrawal of the wire past such fingers (in other words, the resistance to wire movement from the container past the fingers should not adversely affect the wire feeding process).
Other types or wire retaining devices are shown in Japanese Patent Publications JP3133579 and JP3264169. These devices have in common the provision of a plurality of flexible extending members which contact either the inner wall of the container or the outer wall of the core, respectively, and past which flexible extending members the wire is withdrawn. The device in JP3264169 is similar to Dragoo.
A cardboard container having an octagonal section is described in the International Patent Application No. WO 98/52844. This patent application shows a container 1 comprising a box-like body 4 with a wire retaining device 17 to prevent the wire from tangling and a wire conduit device 10 to guide the wire out from the container during the unwinding. The retainer device 17 is made of three rings 18, 19 and 20 joined together by bridging elements 22 which have radial projections 23 dimensioned to be in solid continuous contact with the inner surface of the container wall to prevent the wire from passing through the space near the wall. The wire retaining device of this patent has to be fabricated to exact dimensions in order to fit in the container and achieve its purpose. A guide member 10 is positioned at the top of the container below the cover 1 to guide the welding wire but has the disadvantage that there is not sufficient space for the wire to rapidly unwind. This restriction may cause tangling of the wire inside the container. Since the retainer device 17 is light weight, the friction between projections 23 of the retainer device 17 with the wall of the container results in the descent of the retainer being not as effective as would be expected (in spite of the elastic pull down 30), because small irregularities in the cardboard walls which can impede and even cant the downward travel of the device vertically and uniformly as the wire is consumed. The guiding member 10 has the drawback that it does not at least initially provide sufficient space between the top of the wire coil and the guide member for the wire to spring up naturally at the beginning of the unwinding and thus instead fosters its tangling.
Another cardboard container is described in U.S. Pat. No. 6,237,768 to Cipriani. The container of Cipriani is also made of cardboard but is formed by two box-like parts, an external cubic box 1 intended to provide strength to the assembly and an inner octagonal box 2. The container also includes plastic bags 4 to enclose and seal the welding wire and protect it from air and humidity, as well as a polygonal section core 2b. Although the container of Cipriani has the advantage of being mechanically stronger, it is much more elaborate and expensive than other containers and the present invention.
During transportation and storage of the welding wire, Cipriani utilizes a pressure bar 10 forced downwardly by an elastic strap 9 attached to a hook 7 fixed at the bottom of the container. This bar 10 presses on a pair of rubber members resting between the bar 10 and a ring 12 placed on top of the wire coil. During unwinding of the welding wire, Cipriani proposes to use a guide member 8 having a square base which fits on the cubic box 1. The guide member 8 has a general conical shape and ends in a top flat portion with a central hole 8c through which the wire is extracted from the container. The container of Cipriani comprises a considerable number of parts more than the parts of the present invention, thus adding to the cost and weight of Cipriani's container.
The need therefore exists for a container effective for handling increased volumes of welding wire at such a low cost that it can be readily and also ecologically disposed of after the wire has been transported and withdrawn from the container at the automatic welding machine. The present invention provides such type of container offering a number of advantages over the containers of the prior art and at the same time being effective in the smooth feeding of such wire according to the demanding standards of the automatic welding processes.